Effect of Occupational Exposure on A(H1N1)pdm09 Infection and Hospitalization.

OBJECTIVE: To analyze relationships between occupational exposure and influenza infection and hospitalization during the 2009-2010 pandemic wave and the 2010-2011 influenza seasonal epidemic in Spain. METHODS: Occupations were classified as high, medium, or low risk of influenza exposure. To assess the risk of infection, 588 outpatient cases of influenza confirmed by reverse-transcription polymerase-chain-reaction (RT-PCR) were compared with 588 outpatients without influenza symptoms. To assess the risk of hospitalization, 337 outpatient influenza cases were compared with 337 inpatient influenza cases. RESULTS: The high risk of occupational exposure group was composed only of health care workers. After adjustment for age, sex, vaccination status, and predictive variables of influenza infection, patients with a high risk of occupational exposure had an aOR of 2.14 (95%CI: 1.25-3.66) of being an outpatient influenza case and an aOR of 0.43 (95%CI: 0.20-0.95) of being an inpatient influenza case, compared with those with a low risk. CONCLUSIONS: A high risk of occupational exposure is a risk factor for influenza infection but not for hospitalization.

Effect of influenza vaccination on the prognosis of hospitalized influenza patients.

OBJECTIVES: This study aimed to assess whether influenza vaccination reduces the risk of severe and fatal outcomes in influenza inpatients aged ≥65 years. METHODS: During the 2013-2014 influenza season persons aged ≥65 years hospitalized with laboratory-confirmed influenza were selected in 19 Spanish hospitals. A severe influenza case was defined as admission to the intensive care unit, death in hospital or within 30 days after admission. Logistic regression was used to compare the influenza vaccination status between severe and non-severe influenza inpatients. RESULTS: Of 433 influenza confirmed patients, 81 (19%) were severe cases. Vaccination reduced the risk of severe illness (odds ratio: 0.57; 95%CI: 0.33-0.98). The cumulative number of influenza vaccine doses received since the 2010-2011 season was associated with a lower risk of severe influenza (odds ratio: 0.78; 95% CI 0.66-0.91). CONCLUSION: Adherence to seasonal influenza vaccination in the elderly may reduce the risk of severe influenza outcomes.

Pandemic influenza A (H1N1) infection in pregnant and nonpregnant women in Spain (2009-2010).

The present study aimed to compare the main features of infection with pandemic influenza A virus in pregnant and nonpregnant women admitted to hospitals in Spain during the first waves of the 2009-2010 influenza pandemic. This was a prospective (November 2009 to June 2010), multicenter observational study. All cases were women of reproductive age who had not been vaccinated against seasonal or pandemic influenza A. Influenza infection was confirmed by reverse transcription-polymerase chain reaction (RT-PCR). The sociodemographic and clinical data of all cases were reviewed. A total of 219 inpatients, including 49 pregnant women and 170 nonpregnant women, were enrolled in the study upon admission to participating hospitals. The most substantially different symptoms between the groups were respiratory distress and unilobar consolidation, both of which were more frequent among nonpregnant women. Antibiotics and systemic corticosteroids were more frequently used in nonpregnant women; however, there were no differences in the rates of treatment with antivirals. Our findings indicated that the compared with nonpregnant women, pregnant women in this study did not have significantly different symptoms and were not at increased risk of complications from pandemic influenza virus infection.

Different prognosis in hospitalized patients with influenza one season after the pandemic H1N1 influenza of 2009-2010 in Spain.

BACKGROUND: The present report compares prognosis in hospitalized cases with the H1N1 pandemic virus in two seasons. METHODS: Two series of hospitalized patients with laboratory-confirmed H1N1 pandemic influenza have been compared: 813 in the season 2009-2010 and 707 in the season 2010-2011. A detailed history of variables preceding hospital admission and during hospitalization was obtained by interview and clinical charts. A combined endpoint of death admission to intensive care was used as outcome due to the low number of deaths. Logistic regression was applied in the analysis for adverse outcome. RESULTS: Patients of the second season had different characteristics than in the first one (older, more underlying conditions, more malfunctioning organs and more symptoms). Patients with H1N1 pandemic virus when hospitalized were more frequently directly admitted to ICU during the 2010-2011 season than in the previous season (RR=2·10; 95% confidence intervals CI, 1·55-2·85), as a consequence of a higher presence of sepsis and respiratory distress. These patients also showed during hospitalization a higher risk of ICU admission or death (RR=3·22, 95% CI, 2·15-4·83). After adjusting for the differences in risk factors of adverse outcome, patients in the second season showed a higher risk of ICU admission and/or in-hospital death odds ratio (OR=3·77, 95% CI, 2·30-6·18). CONCLUSION: Hospitalized patients with H1N1 pandemic influenza during the second season were more severely affected at hospital admission and showed a worse prognosis than in previous season, independently of the differences found at hospital admission.

Risk factors and effectiveness of preventive measures against influenza in the community.

BACKGROUND: The role of different risk exposures and preventive measures against influenza has not been well established. OBJECTIVE: The aim of this study was to evaluate risk factors and measures to prevent influenza infection in the community. METHODS: We conducted a multicenter case-control study. Cases were 481 outpatients aged 18 years or older with laboratory-confirmed influenza A(H1N1)09 in the 2009-2010 season in Spain. A control was selected for each case from outpatients from the same area matched by age and date of consultation. Information on risk situations, preventive measures and other variables was obtained by interview and review of the medical record. RESULTS: In the multivariate conditional logistic regression analysis, the risk of a diagnosis of influenza increased with the number of cohabitants (compared with <3 cohabitants, three cohabitants had an OR= 1·80, 95% CI 1·12-2·89, and ≥5 cohabitants had an OR = 2·66, 95% CI 1·31-5·41) and for health care workers (OR = 2·94, 95% CI 1·53-5·66). The use of metropolitan public transport was associated with a lower frequency of a diagnosis of influenza (OR = 0·45, 95% CI 0·30-0·68) but not the use of taxis or long-distance transport. The influenza A(H1N1)09 vaccine had a protective effect (OR =0·13, 95% CI 0·04-0·48), unlike hand washing after touching contaminated surfaces or the use of alcohol-based hand sanitizers. CONCLUSION: The home environment appears to play an important role in the spread of influenza in adults, but not the use of public transport. Health care workers have a higher risk of contracting influenza. Vaccination was the most effective preventive measure.